Well perforating method and apparatus



NOV. 12, 1963 LEBOURG 3,110,257

WELL PERFORATING METHOD AND APPARATUS Filed March 5, 1958 2 Sheets-Sheet1 MW i A 4' 60;

O O O W A 4 m May/me P. 1 ebou/ INVENTOR.

ATTORNEY Nov. 12, 1963 M. P. LEBOURG WELL PERFORATING METHOD ANDAPPARATUS Filed March 5, 1958 2 Sheets-Sheet 2 Mau/vce P leoar INVENTOR.

United States Patent 3,110,257 WELL PERFGRATING METHOD AND AlrARATUSMaurice P. Lehourg, Houston, Tex., assignor to Schlumherger WellSurveying Corporation, Houston, Tex., a

corporation of Texas Filed Mar. 5, 1958, Ser. No. 719,255 9 Claims. (Cl.-2-20) This invention relates to perforating apparatus and moreparticularly pertains to new and improved methods and apparatusincluding shaped explosive charges for perforating well casing.

Shaped explosive charges have been used with considerable commercialsuccess in oil well operations known as Permanent Well Completions. Inthis application, a shaped charge perforating gun is lowered throughproduction tubing of relative small diameter to a level of interestwhere it is used for producing perforations through the larger diameterwell casing. Obviously, a small size and high penetrating power aredesirable in perforating guns of this type.

It has been established that shaped charges generally do not provideoptimum hole size and penetration when tired directly into a target. ithas also been found that as the clearance, that is, the spacing betweenthe charge and the target increases, the penetration increases tooptimum point and then decreases with further increases in clearance.Hole size similarly may vary with the clearance.

Therefore, it is an object of the present invention to provide new andimproved methods and apparatus including shaped explosive charges forperforating well casing which meet size and penetration requisites ofPermanent Well Completion techniques.

it is another object of the present invention to provide new andimproved orienting devices for a shaped charge gun which allowspositioning of the gun in a well casing thereby to allow the hole sizeand penetration to be optimized.

A further object of the present invention is to provide a new andimproved orienting device for a shaped charge gun in which a pluralityof charges may be simply and reliably positioned with respect to thecasing at a given clearance thereby allowing the charges to obtainoptimum penetration at a plurality of spaced points.

Yet another object of the present invention is to provide a new andimproved method of perforating well casing in which both direction andextent of penetration may be reliably established.

These and other objects of the invention are achieved by disposing, in awell casing of ferromagnetic, material, perforating means having a givenperforating axis and orienting the perforating axis by a magnetic forceacting on the well casing along magnetic axis in a longitudinal planeangularly disposed to longitudinal plane containing the aforesaidperforating axis with the planes extending in the same direction as thelongitudinal axis of the casing. Apparatus constructed in accordancewith the present invention therefore includes a support adapted to bedisposed in the casing and magnetic means carried by the support whichis attracted to the casing and thus brings at least a portion of theperforating apparatus into con tact with the inner wall of the casing.The magnetic means has a magnetic axis lying in a first plane extendingin the same direction as the longitudinal axis of the casing. Theperforating means included and carried with the support has aperforating axis lying in a second plane disposed at an angle relativeto the first plane.

T he novel features of the present invention are set forth withparticularity in the amended claims. The present in- Patented Nov. 12,1963 "ice vention, both as to its organization and manner of operationtogether with further objects and advantages thereof, may best beunderstood by reference to the following description taken in connectionwith the accompanying drawings in which:

FIG. 1 is a side elevational view of perforating apparatus embodying theresent invention shown in a well oasing below production tubing;

FIGS. 2A and 2B represent upper and lower portions, respectively, ofapparatus embodying the invention in a view taken along lines ZAB-ZAB ofFIG. 3 and shown partly in cross section;

FIG. 3 is a cross-sectional View taken along lines 33 of FIG. 2A;

FIG. 4 is a cross-sectional view taken along lines 44 of FIG. 2B;

FIG. 5 illustrates a modified form of the apparatus featuring theinvention;

PEG. 6 is similar to H6. 1, however, it illustrates the invention as itmay be employed in dual well completion;

FIG. 7 is a cross-sectional view taken along the lines 7-7 of FIG. 6.

in EEG. l of the drawings, perforating apparatus em bodying the presentinvention is shown disposed in borehole i6 having a well casing 11 andtraversing earth formations i2, 13, -14. it is assumed that formation 13is the one of interest to be perforated in a manner which will be moreapparent from the discussion to follow.

The perforating apparatus comprises a conventional casing collar locator15 to facilitate the positioning of the apparatus, a cylindricalorienting device 15 and a cylin drical perforating gun 16 suspended byan electric cable 1'7 in the Well casing elow the production tubing 18.Cable 17 together with a conventional winch (not shown) are provided forlowering the apparatus into a borehole to a level at which casing 11 :isto be perforated.

Referring now more particularly to H6. 2A and FIG. 2B, the orientingdevice 15 generally consists of a nonmagnetic cyL'ndrical body 26 suchas nonmagnetic stainless steel having a coupling socket 21 at its upperend connected to collar locator 15' and having a stub mandrel 22 at itslower end connected to the gun 16. Body 20 is bifurcated to provide sidearms 23 and 24 separated by a longitudinal slot 25 of, generallyrectangular configuration in transverse section (FIG. 3) that extendsfrom the lower end of body 28 to a transverse wall 25a adjacent thesocket 21. A central opening 26 in wall 25a is aligned with a centralopening 27 in stub mandrel 22 and a tube 23 of electrically insulatingnonmagnetic material, such as Bakelite, extends through the slot 25 andis received by the openings 25 and 27. A rod 29 of the electricallyconductive material extends through the tube 28 and projects from theupper and lower ends of the tube. An upper terminal 3% is connected torod 29 and through cable 17 to a suitable source of current (not shown)at the surface of the earth by means of a conductor 30a and otherconductors not shown. The lower end of rod 29 is connected via aterminal 31 to an electrical conductor 32 that extends to a detonator(not shown) for the perforating gun 16. Appropriate ground connections(not shown) complete the electrical circuit just described.

Magnets are employed in the present invention to bring the device 15into attachment with the casing. Since the device is typicallycylindrical and typically has a much smaller diameter than the innerdiameter of the casing, a generatrix of contact exists between thedevice and the casing. The generatrix of contact is invariably generatedby a certain imaginary line or axis extending lengthwise of the deviceand a line of contact along the casing. The imaginary line or axis alongthe device is a result of the magnetic means developing a resultantradial force of attraction and lies in a definitely located position ina plane which intersects the central axis of the device. As may besurmised, the poles of a magnet can be arranged in various ways so longas the magnets develop a resultant radial force of attraction along animaginary line or axis along the device.

A magnetic arrangement, as shown in FIG. 3, includes elongated permanentmagnets 33 and 34 each having a generally U-shaped configuration intransverse cross section. The magnets are positioned in back-tobackrelation in the slot 25 between the side arms with the magnetic polesextending outwardly so that the magnets are positioned at 180. Betweeneach of the poles lies an axis 33a, 34a (FIG. 3) which represent aresultant radial force of attraction. The axes lie in a plane M whichintersects the longitudinal axis 35 of the body 20. The magnets may beof any suitable material, for example Alnico NoJS. The magnets 33, 34abut tube 28 and a suitable insulating and bonding nonmagnetic plastic,such as commercial Epon or any other suitable binder material, fills thespace 36 between the magnets 33, 34 and the tube and the space 37between the poles of each magnet. The poles of magnets 33, 34 and thefilling material in space 37 are shaped to conform to the cylindricalouter configuration of body 20, as best seen in FIG. 3. The portion ofapparatus embodying the invention, thus far described, is comprised ofmagnetic means having a resultant radical force of attraction lying in aplane M that extends centrally between the respective outward facingmagnetic poles. This plane also intersects the longitudinal axis of thewell casing 11 and extends in the same direction as the longitudinalaxis.

The stud mandrel 22 has threaded radial bores 40 extending into it at 90intervals (FIG. for receiving screws 41. Two of the bores are positionedin the longitudinal plane M extending centrally through the magnets andtwo of the threaded bores are positioned in a longitudinal plane P whichis rotated 90 from the first-mentioned longitudinal plane. This allowsthe perforating unit 16 to be aligned in a longitudinal plane P rotated90 from the longitudinal plane M for reasons which will become moreapparent later.

Turning now to the perforating gun 16 (FIG. 2B), this portion of theapparatus may be constructed in a conventional manner. For example,shaped charge perforating apparatus of the type described in Patent No.2,785,- 631 to A. Blanchard may be employed. Alternatively, theperforating gun may be constructed as disclosed in the copendingapplication of Maurice P. Lebourg, Serial No. 510,129, filed May 23,1955, and assigned to the present assignee. As contemplated for thepresent invention, the charges should be oriented in a selected manner.Preferably, their perforating axis should be positioned to lie in planeP (FIG. 3) which intersects and is at 90 relative to the plane M,although it will be apparent that in accordance with the teachings ofthe invention other angles may be suitably employed. The charges may bephased at a 180 with respect to each other although it will becomeapparent that other positionings may be suitably employed in accordancewith the teachings of this invention. For purposes of illustration thegun, as disclosed in the Lebourg application, will be briefly describedand further reference may be made thereto for specific details notpresently shown.

Referring to FIG. 2B, the perforating gun 16 is comprised of a tubularhousing 43 which is adapted to be coupled to stub mandrel 22 by means ofthe screws 41 and may be constructed of a frangible electricallyconductive material, for example an alloy of aluminum. A plurality ofshaped explosive charge units 44 and 45 are mechanically supportedwithin the tubular housing having their respective jet axes 46 and 47inclined relative V to longitudinal axis 35 of the assembly and inlongitudinal plane P. Each of the charge units includes a hollowcylindrical container 48 for an explosive material 49 having conicalfront recess fitted with a liner 50 and having a primer 51 at itsrearward end.

A booster charge 52 for primer 51 of the lowermost charge 44 isassociated with a blasting cap (not shown) to which electrical lead 32is connected and a ground lead (not shown) is also provided to completethe circuit. A source of electric current (not shown) may be selectivelyconnected to the leads to detonate the blasting cap and, in turn,ignites booster charge 52. The primer 51 is thus ignited and chargematerial 49 detonated thereby to form a perforating jet along the axis46 in a known manner.

A cylindrical booster charge 53 has one end disposed in the path ofmaterial comprising the jet from charge 44 which is formed along axis46. The other end of booster 53 is associated with the primer 51 at therear end of charge material 49 contained by a housing 48 of charge unit45. Consequently, the jet from charge unit 44 ignites the booster 53which, in turn, ignites primer 51 and charge material 49 is detonatedand its perforating jet is formed along axis 47. Although only twocharges have been illustrated and described, obviously any number ofadditional charges may be suitably employed.

In accordance with the teachings of the invention, the

gun 16 is connected to the orienting unit 15 by means of screws 41 andthreaded bores 40 so that the direction of fire is in a longitudinalplane P spaced angularly from longitudinal plane M containing themagnetic axes 33a, 34a.

'In operation the perforating apparatus is lowered through tubing 18into the well casing 11 and one of the magnets 33 or 34 will bemagnetically attracted to the casing. The apparatus slides downwardwhile maintaining magnetic contact with the casing until the zone whereperforating to be accomplished is reached. Since the orienting unit 15determines the position of the perforating apparatus relative to thecasing, perforating unit 16 is positioned so that the axis 46, 47 of theperforating charges 44, 45 lie in plane P. It is obvious that regardlessof the position of perforating apparatus on the inner wall of thecasing, the charges will always be directed in a plane P which is at anangle of 90 relative to plane M.

The spacing between the gun body and the well casing along the jet axisas shown in FIG. 3, thus, will always be constant and equal for bothsides and thus, the clearance can consequently be standard although ahousing for perforating apparatus of minimum size is employed.

To assist the magnets in orienting the apparatus unstabilizing means, asshown in FIG. 5, may be employed. In this modification a pair oflongitudinal ribs 55 are positioned in a longitudinal plane on oppositesides of the body in line with the plane P of the perforating axis. Theribs 55 are of generally triangular cross section in a horizontal planeand converge outwardly to present apices 56. If the ribs contact thecasing 11, the assembly is unstabilized or unbalanced and will tend torotate in either direction, for example, from the position shown in fulllines toward the position shown in dotted-line construction. Thus, oneof the magnets will readily bring the apparatus into engagement with thewell casing with the charges directed in plane P.

FIGS. 6 and 7 illustrate the application of the invention to a dual wellcompletion. As illustrated a portion of the well casing 11 extendsthrough the zone 13 to be perforated and contains a nonmagnetic section60 of a production tubing 61 which is packed-off by conventional packingmeans 62 and 63 from the zone to be perforated. A second productiontubing 64 extends through the packer 62 to the zone to be perforated.When the apparatus is lowered into the casing 11 through the secondproduction tubing 64, it afiixes to the casing in a manner previouslydescribed. Of course, it cannot attach to the nonmagnetic section. Withthe use of the invention the firing of the shaped charges is directed ina plane which does not intersect the production tubing section 60 andthe plane of firing as indicated by arrows 65 will be spaced from theproduction tubing 6t).

Obviously, other forms of magnetic means may be employed in accordancewith the invention. For example, a series of horseshoe magnets or barmagnets may be disposed in plane M in stacked vertical relationship withtheir legs alternating in direction and having a resultant radial forceof attraction longitudinal and parallel to the longitudinal axis of theorienting body. Alternatively, instead of permanent magnets,electromagnets may be employed.

It will now be apparent that this invention has provided a method ofperforating well casing in a reliable manner by positioning a magneticorienting means with respect to a perforating means so that the magneticmeans has a magnetic axis lying in a first longitudinal plane and in anangular relationship to a second longitudinal plane extending throughthe perforating means and lying in the plane of the perforating axis,positioning the means adjacent the zone to be perforated, orienting theplane of the perforating axis by magnetically attracting the magneticmeans to the inner Wall of the well casing and firing the perforatingmeans. It will also be apparent that suitable apparatus for perforatinga ferromagnetic well casing has been provided which consists of anelongated support adapted to be disposed in the casing and having alongitudinal axis, a magnet means carried by the support for bringing atleast a portion of the perforating apparatus into contact with the innerwall of the casing and having a resultant radial force of attractionlying in a first plane which extends in the same direction as thelongitudinal axis of the support, and perforating means carried by thesupport having a perforating axis lying in a second plane which extendsin the same direction as the longitudinal axis of the support where thesecond plane is disposed at an angle relative to the first plane.

While particular embodiments of the present invention have been shownand described, it is apparent that changes and modifications may be madewithout departing from this invention in its broader aspects. Therefore,the aim in the appended claims is to cover all such changes andmodifications as fall within the true spirit and scope of thisinvention.

1 claim:

1. Perforating apparatus for use in well casing of ferro magneticmaterial comprising: an elongated support adapted to be disposed in thewell casing and having a longitudinal axis, said support comprised ofupper and lower coupling members and a bifurcated section joining saidmembers, said members having means defining a bore extendinglongitudinally through said members, and a conductive rod disposedwithin said bore; insulating means covering said rod; U-shaped permanentmagnet means disposed within said bifurcated section having magneticpoles facing outwardly and rear surfaces in back-to-back relation andabutting said insulating means, and having a resultant radial force ofattraction disposed between the poles of the said magnet, said resultantradial force of attract-ion lying in a first longitudinal planecoinciding with the longitudinal axis of said support; a bondingmaterial disposed Within said bifurcated section between said magnetmeans and said insulating means and between the poles of said magnetmews; and perforating means canied by said support including a pluralityof shaped charges arranged to fire in different directions and definingtherebetween an angular zone of non-firing; and means for detachablysecuring said perforating means to said support with said resultantradial force of attraction substantially bisecting said angularnon-firing Zone.

2. Perforating appanatus for use in well casing of ferromagneticmaterial comprising: an elongated support adapted to be disposed in thewell casing and having a longitudinal axis, said support comprised ofupper and lower coupling members and a bifurcated section joining saidmembers, said members having means defining a bore extendinglongitudinally through said members and a conductive rod disposed Withinsaid bore; insulating means covering said rod; U-shaped permanent magnetmeans disposed within said bifurcated section having magnetic polesfacing outwardly and rear surfaces in back-toback relation and abuttingsaid insulating means, and having a resultant radial force 'ofattraction disposed between the poles of the said magnet, said resultantradial force of attraction lying in a first longitudinal planecoinciding with the longitudinal axis of said support; a bondingmaterial disposed within said bifurcated section between said magnetmeans and said insulating means and between the poles of said magnetmeans; and perforating means coupled to said support and including aplurality of shaped charges having forward end portions disposed alongperforating axes which are aligned in a second plane intersecting saidcentral axis, said shaped charges being arranged so that alternateforward end portions face in opposed directions relative to said centralaxis, said second plane being angul-arly disposed relative to said firstplane at an angle of 99.

3. Well perforating apparatus comprising a perforating gun section and amagnetic gun orienting section in endwise longitudinal alignment, saidorienting section having a generally cylindrical profile of sufficientdiameter to include the longitudinally projected profile of said gunsection, U-shaped permanent magnet means carried by said orientingsection and having its opposite po-le faces terminating substantially atthe cylindrical profile of said orienting section and symmetricallydisposed With respect to a longitudinal plane of symmetry to develop aresultant radial force of attraction in said plane of symmetry, firstand second groups of shaped charges carried by said gun section forfiring in first and second directions, said gun section having anangular zone of non-firing intermediate said directions, and means fordetachably securing said sections endwise in alignment, with said planeof symmetry substantially bisecting said angular non-firing zone.

4. Well perforating apparatus comprising a perforating gun section and amagnetic gun orienting section in endwise longitudinal alignment, saidorienting sect-ion having a generally cylindrical profile of sufficientdiameter to include the longitudinally projected profile of said gunsection, Uashaped magnet means carried by said orienting section andhaving its opposite pole faces terminating substantially at thecylindrical profile of said orienting section and circumferentiallyspaced on one side thereof symmetrically with respect to a longitudinalplane of symmetry to develop a resultant radial force of attraction insaid plane of symmetry, first and second groups of shaped chargescarried by said gun section for firing in first and second directionswhich define an angular zone of non-firing intermediate said directions,and means for detachably securing said sections endwise in alignment,with said plane of symmetry substantially bisecting said angularnon-firing zone.

5. Well perforating apparatus comprising a perforating gun section and amagnetic gun orienting section in endwise longitudinal alignment, saidorienting section having a generally cylindrical profile or sufiicientdiameter to include the longitudinally projected profile of said gunsection, U-shaped magnet means carried by said orienting section andhaving its opposite pole faces terminating substantially at thecylindrical profile of said orienting section and symmetrically disposedwith respect to a longitudinal plane of symmetry to develop a resultantradial force of attraction in said plane of symmetry, non-mag neticmeans disposed between said pole faces and shaped 7 to conform to saidcylindrical profile, first and second groups of shaped charges carriedby gun section for firing in first and second directions, definingtherebetween an angular zone of non-firing, and means for cletachablysecuring said sections with said plane of symmetry substantiallybisecting said angular non-firing zone.

6. Well perforating apparatus comprising a perforating gun section and amagnetic gun orienting section in endwise longitudinal alignment, saidorienting section having a generally cylindrical profile or sufficientdiameter to include the longitudinally projected profile of said gunsection, U-shaped magnet means carried by said orienting section andhaving its opposite pole faces terminating substantially at thecylindrical profile of said orienting section and symmetrically disposedwith respect to a longitudinal plane of symmetry to develop a resultantradial force of attraction in said plane of symmetry, first and secondgroups of shaped charges carried by said gun section for firing in firstand second directions, defining therebetween an angular zone ofnon-firing of not more than 180, and means for detachably securing saidsections endwise in alignment with said plane of symmetry substantiallybisecting said angular non-firing zone.

7. Well perforating apparatus comprising a perforating gun section and amagnetic gun orienting section in endwise longitudinal aligment, saidorienting swtion having a generally cylindrical profile of suflicientdiameter to in clude the longitudinally projected profile of said gunsec tion, U-shaped magnet means carried by said orienting section andhaving its opposite pole faces terminating subst-antially at thecylindrical profile of said orienting section and symmetrically disposedwith respect to a longitudinal plane of symmetry to develop a resultantradial force of attraction in said plane of symmetry, first and secondgroups of shaped charges earned by said gun section for firing in firstand second directions, defining therebetween an angular zone ofnon-firing, means for detachably securing said sections with said planeof symmetry substantially bisecting said angular non-firing zone, and afiring circuit extending through said sections detachably connected attheir junction.

8. The method of perforating a ferromagnetic casing in a zone below onetubing string set in the casing comprising the steps'of loading shapedcharges into a perforating gun with two directions of firing spaced 'byan angular non-firing zone, securing endwise to said gun a U-shapedpermanent magnet having its opposite pole faces spaced symmetricallywith respect to a longitudinal plane substantially bisectin-g saidangular non-firing zone, lowering the magnet and gun on a cable throughthe tubing string to said zone to develop a resultant force ofattraction between said magnet and the casing in said zone acting insaid plane of symmetry sufficient to secure said gun to said casingalong a prescribed line of contact extending the length of said gun, andthen supplying current through the cable to fire the shaped charges awayfrom said line of contact.

9. In a dual Well completion in a well casing where a first productiontubing extends through the casing to a lower production zone and asecond production tubing extends through the casing to an upperproduction zone, the method of perforating the upper production zonecomprising the steps of: positioning a magnetic orienting means having aresultant radial force of attraction in a longitudinal plane withrespect to a perforating apparatus having different directions of firingdefining an angular zone of non-firing so that the resultant radialforce of attraction substantially bisects the zone of non-firing,disposing said means adjacent the upper production zone and below thesecond production tubing to orient the plane of the resultant radialforce of attraction, and firing said perforating apparatus.

References Cited in the file of this patent UNITED STATES PATENTS2,616,370 Foster Nov. 4, 1952 2,664,162 Howard et a1. Dec. 29, 19532,669,928 Sweetman Feb. 23, 1954 2,719,485 Bendar Oct. 4, 1955 2,729,494Trowbridge Jan. 3, 1956 2,778,669 Goodwin Jan. 22, 1957 2,785,754 TrueMar. 19, 1957 2,796,023 Abendroth June 18, 1957 2,853,944 RobertsonSept. 30, 1958 2,891,620 Bielstein June 23, 1959 FOREIGN PATENTS 211,094Australia Nov. 8, 1956

3. WELL PERFORATING APPARATUS COMPRISING A PERFORATING GUN SECTION AND AMAGNETIC GUN ORIENTING SECTION IN ENDWISE LONGITUDINAL ALIGNMENT, SAIDORIENTING SECTION HAVING A GENERALLY CYLINDRICAL PROFILE OF SUFFICIENTDIAMETER TO INCLUDE THE LONGITUDINALLY PROJECTED PROFILE OF SAID GUNSECTION, U-SHAPED PERMANENT MAGNET MEANS CARRIED BY SAID ORIENTINGSECTION AND HAVING ITS OPPOSITE POLE FACES TERMINATING SUBSTANTIALLY ATTHE CYLINDRICAL PROFILE OF SAID ORIENTING SECTION AND SYMMETRICALLYDISPOSED WITH RESPECT TO A LONGITUDINAL PLANE OF SYMMETRY TO DEVELOP ARESULTANT RADIAL FORCE OF ATTRACTION IN SAID PLANE OF SYMMETRY, FIRSTAND SECOND GROUPS OF SHAPED CHARGES